This invention relates to ar-halo-ar-alkylstyrene monomers, polymers and curable molding compositions containing such monomers.
Polymers of styrene and various ring substituted styrenes are known to be useful in molding applications and the like. In many molding and similar applications, however, the conventional styrene polymers do not possess enough heat resistance and/or the ability to be cured rapidly.
Also it is known to prepare curable molding compositions of crosslinkable polymers, e.g., unsaturated polyesters, and styrene monomers. In curing such compositions with the use of free-radical generating catalysts, e.g., t-butyl perbenzoate, t-butylperoctoate, dicumyl peroxide and the like, and heat, it is greatly desirable to effect complete curing within a relatively short period of time at minimum temperature. In many applications, it is also desirable that the resulting cured compositions exhibit resistance to high temperatures and at least a minimum degree of flame resistance.
While styrene and many known substituted styrene monomers impart desirable qualities to the cured compound such as stiffness, the time required to gel such curable compositions and the temperature increase during curing are often excessive and therefore uneconomical. Additionally, exposure to the relatively high temperatures during curing often has a deleterious effect on the cured product, e.g., the existence of thermal stresses in the polymers of the cured product when such polymers are cooled to use temperatures. Such high temperatures during curing necessitate the employment of massive pressure equipment in order to make good moldings.
In view of the foregoing disadvantages of conventional styrene polymers and of curable compositions employing styrene or conventional styrene monomers, it would be highly desirable to provide monomers (1) which polymerize to heat resistant materials and (2) which, when substituted for styrene in conventional curable compositions, enable the compositions to gel in shorter times and to cure at lower temperatures. Such monomers would offer the great commercial advantage of enabling the use of fast mechanical presses employing essentially contact pressures instead of slow hydraulic presses.